The Laboratory Core has been devised to provide efficient data production and management in an environment requiring large numbers of serial samples to be processed for multiple hormonal analyses. Dedicated personel will utilize newly renovated facilities in the Section of Endocrinology of the University of Chicago. The use of certain instruments (centrifuges, the DPC Immulite Automated Immunoassay Analyzer, and the HPLC system) will be shared in use with the Ligand Assay Core of the University of Chicago Diabetes Research and Training Center (DRTC). The main goals of the Laboratory Core are to provide Program Projects 6, 7 and 8 with accurate and reproducible measurements of: 1) Blood levels of hormones that are affected by aging and/or sleep duration and quality, including cortisol, leptin, insulin, C-peptide, growth hormone, insulin-like growth factor-1, thyroid stimulating hormone, free triiodothyronine, melatonin, testosterone and estradiol. 2) Urinary and plasma levels of epinephrine and norepinephrine, which together with cardiovascular indices of autonomic function will provide an integrated assessment of the impact of age and sleep duration and quality on sympathetic nervous activity. 3) Markers of inflammation, including Creactive protein, interleukin-6, and tumor necrosis factor-alpha, which are modulated by sleep and aging, and are elevated in subjects at risk for diabetes and cardiovascular disease. 4) Salivary cortisol and melatonin levels to allow the estimation of the onset of nocturnal melatonin secretion, a marker of circadian phase affected by aging, and the decline of cortisol secretion, a marker of hypothalamo-pituitary-adrenal function modified by sleep loss, stress, and older age. 5) Biochemical indices of bone metabolism, including serum osteocalcin and bone specific alkaline phosphatase as markers of bone formation, and serum CTX and urinary NTX as markers of bone resorption. Cost sharing of assays and major equipment needed to perform these measurements with the DRTC will significantly reduce the overall cost of these services to the Program Project. In addition to providing critical support for the implementation of Projects 7, 8 and 9, the Laboratory Core will also provide centralized records of all hormonal measurements from studies performed under the auspices of the Program Project, maintainance of records of assay standards and characteristics, and exploration of the potential use of novel analytical techniques.